When the "Start" button is clicked, the Logic software begins recording data into the pre-trigger buffer until the trigger even occurs.
In cases where the trigger event occurs almost immediately after the "Start" button is clicked, it may seem that the "pre-trigger buffer size" setting was ignored and the buffer may look incomplete.
For example, if "pre-trigger buffer size" was set to 100 ms, and the trigger occurs 10 μs after your click "Start", then the pre-trigger buffer will only contain 10 μs of recorded data, and not the full 100 ms that was expected. This might be the case for fast periodic signals that can cause a trigger event shortly after the "Start" button is clicked.
trello ID: 590a7fea9b9dcc39e1d1e505